Limited information is available regarding the methodology required to characterize hashish seizures for
assessing the presence or the absence of a chemical link between two seizures. This casework report
presents the methodology applied for assessing that two different police seizures were coming from the
same block before this latter one was split.
The chemical signature was extracted using GC–MS analysis and the implemented methodology
consists in a study of intra- and inter-variability distributions based on the measurement of the chemical
profiles similarity using a number of hashish seizures and the calculation of the Pearson correlation
coefficient. Different statistical scenarios (i.e., a combination of data pretreatment techniques and
selection of target compounds) were tested to find the most discriminating one.
Seven compounds showing high discrimination capabilities were selected on which a specific
statistical data pretreatment was applied. Based on the results, the statistical model built for comparing
the hashish seizures leads to low error rates. Therefore, the implemented methodology is suitable for the
chemical profiling of hashish seizures